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United States Patent |
5,286,174
|
Fujiwara
,   et al.
|
February 15, 1994
|
Fluid compression device
Abstract
A fluid compressor including a sealed case having an oil bank in which oil
is held, a cylinder arranged in the sealed case, a rotation body
eccentrically arranged in the cylinder, a main shaft and a sub-shaft
formed at each of axial end portions of the rotation body, a spiral groove
formed on a periphery thereof such that a pitch of the spiral groove
gradually decreases from the sub-shaft side to the main shaft side, a
spiral blade engaged with the groove such as to be able to project
therefrom or retreat therein, a main bearing and a sub-bearing for
eccentrically supporting the cylinder and the rotation body, and a suction
hole provided in the rotation body for allowing an operation fluid having
a low pressure before compression to flow from the main shaft side to the
sub-shaft side so as to introduce the fluid into an inner space of the
cylinder, the cylinder and the rotation body rotated relatively with each
other so as to transport the operation fluid from the sub-shaft side to
the main shaft side for compression.
Inventors:
|
Fujiwara; Takayoshi (Kawasaki, JP);
Iida; Toshikatsu (Yokohama, JP);
Honjo; Takashi (Tokyo, JP);
Okuda; Masayuki (Yokohama, JP)
|
Assignee:
|
Kabushiki Kaisha Toshiba (Kawasaki, JP)
|
Appl. No.:
|
015791 |
Filed:
|
February 10, 1993 |
Foreign Application Priority Data
| Feb 10, 1992[JP] | 4-023975 |
| Aug 28, 1992[JP] | 4-229890 |
Current U.S. Class: |
417/356; 418/183; 418/220 |
Intern'l Class: |
F04C 018/16 |
Field of Search: |
417/356
418/220,183,164,172
|
References Cited
U.S. Patent Documents
4521169 | Jun., 1985 | Ogawa | 418/164.
|
4527968 | Jul., 1985 | Ogawa | 418/164.
|
4871304 | Oct., 1989 | Iida et al. | 418/304.
|
4872820 | Oct., 1989 | Iida et al. | 418/220.
|
4875842 | Oct., 1989 | Iida et al. | 418/220.
|
5028222 | Jul., 1991 | Iida | 418/220.
|
5062778 | Nov., 1991 | Hattori et al. | 418/220.
|
5090874 | Feb., 1992 | Aikawa | 418/220.
|
5125805 | Jun., 1992 | Fujiwara | 418/220.
|
5139394 | Aug., 1992 | Aikawa et al. | 418/220.
|
5141423 | Aug., 1992 | Aikawa et al. | 418/220.
|
5184940 | Feb., 1993 | Fujiwara | 418/220.
|
Foreign Patent Documents |
4-63990 | Feb., 1992 | JP | 418/220.
|
Primary Examiner: Bertsch; Richard A.
Assistant Examiner: Korytnyk; Peter
Attorney, Agent or Firm: Cushman, Darby & Cushman
Claims
What is claimed is:
1. A fluid compressor comprising:
a sealed case having an oil bank in which oil is held;
a cylinder arranged in said sealed case;
a rotation rod, having a main body portion with a spiral groove therein and
having a suction hole therethrough, eccentrically arranged in said
cylinder;
a main shaft formed at one of the axial end portions of said rotation rod,
and a sub-shaft formed at the other end thereof; decreasing from said
sub-shaft side to said main shaft side;
a spiral blade engaged with said groove such as to be able to project
therefrom or retreat therein;
a main bearing and a sub-bearing for eccentrically supporting said cylinder
and said rotation rod, an inner surface of the main bearing and an end
face of the main shaft defining an inner cavity located at the main shaft
side of the rotation rod; and
a suction tube, connected to the inner cavity, for allowing a low pressure
operation fluid to flow through a wall of the sealed case and into the
inner cavity, said suction hole provided in said rotation rod and
connected to the inner cavity allowing the low pressure operation fluid to
flow from the inner cavity at the main shaft side to said sub-shaft side
so as to introduce said fluid into an inner space of said cylinder;
said cylinder and said rotation rod being rotatable with respect to each
other so as to compress said operation fluid as the operation fluid is
transported from said sub-shaft to said main shaft side;
wherein a thrust force acting on the rotation rod resulting from the
compression of the operation fluid is at least partially balanced by an
opposing thrust force on the rotation rod resulting from the low pressure
operation fluid in the inner cavity acting on the end face of the main
shaft side of the rotation rod.
2. A fluid compressor according to claim 1, wherein said rotation rod
includes an oil feeding hole serving to send said oil from said sub-shaft
side to said main shaft side.
3. A fluid compressor according to claim 2, wherein said suction hole and
said oil feeding hole are arranged symmetrically with respect to an axial
center of said rotation rod.
4. A fluid compressor according to claim 2, wherein a discharge tube is
connected to said sealed case, and said cylinder has a discharge hole at
one end thereof, said discharge tube arranged at a position close to an
other end of said cylinder, and said discharge tube and said discharge
hole being distant from each other.
5. A fluid compressor according to claim 2, further comprising a rotation
force propagation mechanism arranged such that an outlet of said oil
feeding hole faces thereto.
6. A fluid compressor according to claim 6, wherein said rotation force
propagation mechanism is of an Oldham type.
7. A fluid compressor according to claim 2, further comprising an oil
feeding pump for compulsively transporting said oil to said oil feeding
hole.
8. A fluid compressor according to claim 7, wherein said oil feeding pump
is of a trochoid type.
9. A fluid compressor according to claim 7, wherein said oil feeding pump
is of a spiral blade type.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluid compressor, more specifically to a
type for compressing a refrigerant gas in a refrigerating cycle.
2. Description of the Related Art
USP Nos. 4,871,304, 4,872,820, and 5,082,222, for example, disclose fluid
compressors of a type in which the refrigerant gas of the refrigerating
cycle is compressed while conveying the gas in the axial direction of the
cylinder.
There is also another type of fluid compressor as shown in FIG. 7. In a
general compressor, refrigerant gas is taken into the device from a main
bearing 1 side, and compressed toward a sub-bearing 2 side. However, in a
fluid compressor of this type, a thrust force works on a rotation rod 3
due to pressure difference of the refrigerant gas. In order to balance the
thrust force, a pressure introduction hole 4 is formed in the rotation rod
3. Refrigerant gas at a suction pressure is introduced into an internal
cavity 5 of the sub-bearing 2, and an end face of a sub-axis 6 of the
rotation rod 3 is pressurized. The diameters of the sections of the
rotation rod 3 are determined such as to cancel out thrust forces for
balance.
The diameter of the main body of the rotation rod 3 is set to be larger
than that of a main shaft 9. The main shaft 9 is inserted into an internal
cavity 10 of the main bearing 1. A part of the end surface 11 of the main
body 8 and a part of the end face 12 of the main bearing 1 face closely
with each other. A suction hole 13 is formed in the main bearing 1, and
serves to connect a suction tube 15 associated with a sealed case 14, and
an inner space of a cylinder 16 with each other. The refrigerant gas
passes through the suction hole 13, and is introduced to the operation
chamber formed in the cylinder 16.
FIG. 7 also depicts a discharge tube 17, which is connected to the sealed
case 14 to be associated with the inner space thereof.
In a fluid compressor of the above-described type, a refrigerant gas is
used to balance thrust forces. Consequently, the diameter of each of the
main shaft 9 and the sub-shaft 6 of the piston must be determined such as
to have a sufficiently large cross section area. However, as the diameter
of the main shaft 9 increases, the thickness of the main bearing 1
decreases.
In order for the cylinder 16 to take a sufficient amount of the refrigerant
gas therein, the suction hole 13 should have a large passage area.
However, if the diameter of the suction hole 13 is simply set large, the
opening of the suction hole 13 is partially covered by the end face 11 of
the main body 8, and therefore the amount of the gas taken in the cylinder
does not increase.
In consideration of the above, in order to have a sufficiently larger
passage area, there should be provided a plurality of suction holes 13 as
shown in FIG. 8A, or the suction hole 13 should be made into a deformed
elliptic shape as in FIG. 8B, thereby increasing the production cost of
the main bearing.
Further, the pressure introduction hole 4 and the suction hole 13 must be
separately provided, and the pressure introduction hole 4 is the main
factor of increasing the production cost.
SUMMARY OF THE INVENTION
The purpose of the invention is to provide a fluid compressor in which
there is no need to provide a suction hole in its main bearing, and
therefore processing of parts is simple.
In order to achieve the above purpose, there is provided, according to the
present invention, a fluid compressor comprising: a sealed case having an
oil bank in which oil is held; a cylinder arranged in the sealed case; a
rotation body eccentrically arranged in the cylinder; a main shaft and a
sub-shaft formed at each of axial end portions of the rotation body; a
spiral groove formed on a periphery thereof such that a pitch of the
spiral groove gradually decreases from the sub-shaft side to the main
shaft side; a spiral blade engaged with the groove such as to be able to
project therefrom or retreat therein; a main bearing and a sub-bearing for
eccentrically supporting the cylinder and the rotation body; and a suction
hole provided in the rotation body for allowing an operation fluid having
a low pressure before compression to flow from the main shaft side to the
sub-shaft side so as to introduce the fluid into an inner space of the
cylinder;
the cylinder and the rotation body rotated relatively with each other so as
to transport the operation fluid from the sub-shaft side to the main shaft
side for compression.
According to the present invention, there is no need to form a suction hole
in the main bearing, and therefore process of parts of the fluid
compressor can be simplified.
Additional objects and advantages of the invention will be set forth in the
description which follows, and in part will be obvious from the
description, or may be learned by practice of the invention. The objects
and advantages of the invention may be realized and obtained by means of
the instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part
of the specification, illustrate presently preferred embodiments of the
invention, and together with the general description given above and the
detailed description of the preferred embodiments given below, serve to
explain the principles of the invention.
FIG. 1 is a cross section of a compressor according to an embodiment of the
present invention;
FIG. 2 is an explanatory view of the opening of a suction hole for
position;
FIG. 3 is a cross section of a main portion taken along the line D--D shown
in FIG. 1;
FIG. 4 is a development of a rotation force propagation mechanism;
Each of FIGS. 5A and 5B is a diagram showing a trochoid-type oil feeding
pump;
FIG. 6 is a spiral blade type oil feeding pump;
FIG. 7 is a cross section of a conventional compressor; and
FIGS. 8A and 8B are cross sections of conventional main bearings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention will now be described with reference
to accompanying drawings.
FIG. 1 shows an embodiment of the present invention, depicting a fluid
compressor 21, and a compression mechanism section 22 of the compressor
21. The compression mechanism portion 22 is housed in a sealed case 23
along with a motor 46. The compression mechanism portion 22 includes a
cylinder 24 having both axial ends opened, and a rotation rod 25 serving
as a rotation body eccentrically arranged in the cylinder 24.
The rotation rod 25 consists of a main body 26, and a main shaft 27 and a
sub-shaft 28 each having a diameter smaller than that of the main body 26.
On the periphery of the main body 26, there is formed a spiral groove 29,
with which a spiral blade 29a is engaged.
The blade 29a is set such as to be able to project from or retreat in the
groove 29 in the radial direction of the main body 26. The outer surface
of the blade 29a is brought into contact with the inner surface of the
cylinder 24 such as to break up the space defined between the cylinder 24
and the rotation rod 25 into a number of operation chambers 49. The pitch
of the groove 29 is set such as to decrease gradually from an end of the
main body 26 to the other end (from the left hand side to the right hand
side in the figure), and therefore the volume of the operation chambers 49
formed in the cylinder 24 gradually decreases.
A main bearing 30 is fixed in the sealed case 23. The main bearing 30 is
made into a step-cylindrical shape, and inserted into an end of the
cylinder 24. The main bearing 30 has an inner cavity 31 made therethrough
in the axial direction, in which the main shaft 27 of the rotation rod 25
is inserted. The outer surface of the main shaft 27 is brought into
contact with the inner surface of the main bearing 30.
A sub-bearing 32 is inserted to the other end of the cylinder 24, and the
sub-shaft 28 of the rotation rod 25 is inserted to the inner cavity of the
sub-bearing 32. The inner cavity 33 of the sub-bearing 32 has a bottom,
and one end of the inner cavity 33 is closed. The outer surface of the
sub-shaft 28 is brought into contact with the inner surface of the
sub-bearing 32.
A suction hole 34 and an oil feeding hole 35, each having a circular cross
section, are formed in the rotation rod 25. The suction hole 34 runs from
the main shaft 27 to the end portion of the sub-shaft 28 side of the main
body 26, in substantially parallel with the axial center 25a of the
rotation rod 25. The end portion of the sub-shaft 28 side of the suction
hole 34 is bent at substantially right angle, and extends in the radial
direction of the rotation rod 25.
One end of the suction hole 34 is opened as an inlet to the end face 36 of
the main shaft 27. The other end of the suction hole 34 is opened to the
outer surface at the sub-shaft side of the rotation rod 25.
This open end (outlet 34a) faces to a rotation force propagation mechanism
40 (described after).
The position of the opening 37 of the suction hole 34 in the sub-shaft 28
side of the rotation rod 25 is determined as shown in FIG. 2. The position
of the opening 37 is not strictly set to a particular section of the
cylinder as long as it is located in a low-pressure section thereof, but
should preferably be at a position where the suction hole 34 has the
shortest depth, which can be easily processed. More specifically, the
suction hole 34 is located at a position close to a line 38 connecting an
origin A of the groove 29 and a point B where the phase of the groove 29
is 360.degree. , and on the main shaft 27 side.
The oil feeding hole 35 runs from the sub-shaft 28 to the main shaft 27 in
substantially parallel with the axial center 25a of the rotation rod 25.
The end of the main shaft 27 side of the oil feeding hole 35 is bent at
substantially right angle and extends in the radial direction of the
rotation rod 25. The oil feeding hole 35 is opened to the end face 39 of
the sub-shaft 28, and also to the border section between the main body 26
and the main shaft 27.
The suction hole 34 and the oil feeding hole 35 are formed symmetrical with
respect to the axial center 25a of the rotation rod 25. The sections of
both holes 34 and 35 extending in their radial directions are formed to
face in directions opposite from each other.
The rotation force propagating mechanism 40, which utilizes an Oldham
mechanism, is provided in the cylinder 24. The mechanism 40 is located at
the border section between the main body 26 and the mainshaft 27, and
serves to connect the rotation rod 25 loosely to the cylinder 24.
As shown in FIG. 4, the rotation force propagating mechanism 40 comprises a
fixed ring 50, a movable ring 51, and a rotation body Oldham section 52.
The rotation body Oldham section 52 is formed integrally with the rotation
rod 25. The outer diameter of the fixed ring 50 is set such as to be
substantially the same as the inner diameter of the cylinder 24, and the
outer diameter of the movable ring 51 is set such as to be smaller than
that of the fixed ring 50.
The movable ring 51 is engaged with the rotation body Oldham section 52.
The fixed ring 50 is fixed to the cylinder 24, and the movable ring 51 is
engaged with the fixed ring 50. With this structure, the movable ring 51
can slide in the two directions normally crossing with each other as being
engaged with the rotation body Oldham section 52 and the fixed ring 51.
An oil suction tube 41 is connected to the sub-bearing 32. The oil suction
tube 41 is inserted in the sub-bearing 32 in the radial direction. The
lower end of the oil suction tube 41 reaches the oil 42 held in the oil
bank 42a of the sealed case 23, and the upper end of the tube is opened to
the inner cavity 33 of the sub-bearing 32.
Inside the sub-bearing 32, there is provided an oil feeding space 43
utilizing the inner cavity 33, and the oil feeding space 43 is defined by
the inner surface of the sub-bearing 32 and the end face 39 of the
sub-shaft 28. The oil feeding space 43 is connected to the inner space of
the sealed case 23 via the oil suction tube 41.
The cylinder 24 has a discharge hole 44. This discharge hole 44 is located
at the end of the discharge side (the right hand side in FIG. 1) of the
cylinder 24, and is opened to the rotational force propagating mechanism
40 and the motor 46.
A suction tube 52 and a discharge tube 53 are connected to the sealed case
23. The suction tube 52 is located on an imaginary extended line from the
axial center 25a of the rotation rod 25, and projects into the inner
cavity 31 of the main bearing 30.
The discharge tube 53 is located on the other side of the sealed case 23,
from where the suction tube 52 is located, i.e. the sub-bearing 32 side.
The discharge tube 53 is located outside the outer surface of the
sub-bearing 32.
The motor 46 comprising a stator 47 and a rotor 48. The stator 47 is fixed
to the case 23, and the rotor 48 is located on an inner side from the
stator 47, and fixed to the cylinder 24. The motor 46 is interposed
between the discharge hole 44 and the discharge tube 53.
The operation of the above-described fluid compressor 21 will now be
described.
The compression mechanism 22 is driven by the motor 46 to rotate the
cylinder 24, and the rotation force of the cylinder 24 is propagated to
the rotation rod 25 via the rotation force propagation mechanism 40, so as
to make the cylinder 24 and the rotation rod 25 rotate relatively with
each other. The rotation angle of the rotation rod 25 is set such as to
accord with that of the cylinder 24 by the rotation force propagation
mechanism 40 The rotation rod 25 and the cylinder 24 are allowed to change
the relative position therebetween by the rotation force propagation
mechanism 40.
As the cylinder 24 and the rotation rod 25 rotates relatively with each
other, for example, refrigerant gas in the refrigerating cycle is absorbed
into the inner cavity 31 of the main bearing 30 via the suction tube 52.
The refrigerant gas is introduced to the sub-shaft 28 side through the
suction hole 34, and flows out to the inner space of the cylinder 24, i.e.
a suction chamber 49a, from the opening 37. The suction chamber 49a is
located at the endmost one having the lowest pressure, of the operation
chambers 49.
The refrigerant gas flown out of the opening 37 is compressed while being
gradually transported to the discharge side, i.e. the main shaft 27 side,
as indicated by arrows C in FIG. 1. The compressed gas is transported from
the discharge chamber 49 through the discharge hole 44, and discharged
into the sealed case 23. The discharge chamber 49b is located at the
endmost one having the highest pressure, of the operation chambers 49.
The refrigerant gas discharged into the case 23 once fills the inner space
of the case 23, and then is introduced to an external device via the
discharge tube 53.
The oil 42 held in the sealed case 23 is pressurized by the refrigerant gas
in the case 23, and a portion of it travels up the suction tube 41. The
portion of the oil 42 is absorbed up once in the feeding space 43 in the
sub-bearing 32, and then flows into the feeding hole 35. The portion of
the oil 42 passes through the oil feeding hole 35 and reaches the main
shaft 27 side. Further, the portion flows out of the rotation rod 25, and
is supplied to the rotation force propagation mechanism 40 and the slide
sections of other members.
Of the structural members of the compressor 21, those which slide with each
other are as follows:
The combinations of the blade 29a and the rotation rod 25, the blade 29a
and the cylinder 24, the cylinder 24 and each of the bearings 30 and 32,
the main shaft 27 of the rotation rod 25, and the sub-shaft 28 and the
sub-bearing 32. In the rotation force propagation mechanism 40, the
members slide with each other.
The portion of oil introduced in the discharge chamber 49b is discharged
from the discharge hole 44 of the cylinder 24 along with high-pressure
refrigerant gas. Since the refrigerant gas is highly pressurized, the oil
is atomized and dispersed in the inner space of the case 23.
A portion of the atomized oil collides with the inner wall of the case 23
and the outer surface of the main bearing 30. Other portion of the
atomized oil collide with the stator 47 of the motor 46, the rotor 48
itself, winding lines for these, etc. After the oil ejected from the
discharge hole 44 of the cylinder 24 collide with the members therearound,
the oil eventually returns to the oil bank 42a as in the original state.
FIG. 1 also depicts an oil feeding passage 54, through which the oil 42
flows. The feeding passage 54 comprises an oil suction tube 41, an oil
feeding space 43, an oil feeding hole 35, a discharge chamber 49b, and
discharge hole 44.
Of the inner and outer portions of the main bearing 30, and those of the
sub-bearing 32, the outer portion 55 of the main bearing 30 is not
affected by a pressure difference, an oil groove 56 should be provided
such as to be integrated with the outer portion 55, for introduction of
the oil 42. The oil introduced in the oil groove 56 flows along the groove
as the cylinder 24 rotates, and lubricates the inner surface of the
cylinder 24 with the outer portion 55 of the main bearing 30.
In the above-described fluid compressor 21, a suction hole 34 is provided
in the rotation rod 25 such that refrigerant gas is introduced in the
cylinder 24 via the rotation rod 25. Consequently, it is no need to make a
suction hole in the main bearing 30, simplifying process of the main
bearing 30. The number of suction holes, or the shape of each one are free
from the relationship between the rotation rod 25 and the main bearing 30
in diameter size.
Further, the flow amount of the refrigerant gas can be determined only by
the size of the suction hole 34 of the rotation rod 25, and therefore
there should be only one suction hole 34. Consequently, process of the
suction hole 34 is carried out.
Thus, the process cost for each of the rotation rod 25 and the main bearing
30 can be kept low.
Unlike the conventional type fluid compressor (for example, U.S. Pat. No.
5,028,222), the refrigerant gas is once introduced in the inner cavity 31
of the main bearing 30, and therefore the low-pressure refrigerant gas
acts on the end face 36 of the main shaft 27. Consequently, there is no
need to provide a pressure introduction hole, reducing the number of
holes. Thus, the process cost is reduced.
Further, the suction hole 34 and the oil feeding hole 35 are symmetrically
arranged at positions opposite to each other with respect to the axial
center 25a of the rotation rod 25. Thus, the rotation rod 25 can be easily
balanced, suppressing vibration of the rotation rod 25.
The rotation force propagation mechanism 40 is located at the border
section between the main body 26 of the rotation rod 25 and the main shaft
27, and a portion of the oil 42 is introduced to the main shaft 27 side.
With this structure, oil 42 can be directly supplied to the rotation force
propagation mechanism 40, carrying out sufficient lubrication thereof.
A discharge hole 44 is located at one end of the cylinder 24, and a
discharge tube 53 is located close to the sub-bearing 32. A motor 46 is
interposed between the discharge hoe 44 and the discharge tube 53, which
are arranged by a great distance from each other. Consequently, atomized
oil ejected from the discharge hole 44 hardly reaches the discharge tube
53, thereby reducing the amount of oil flowing out of the case 23 from the
discharge tube 53, and assuring sufficient lubrication of the sliding
members.
A portion of the oil ejected from the discharge hole 44 serves to cool the
motor 46, improving the driving efficiency of the compressor.
In the case where the pressure of the refrigerant gas is not utilized for
feeding oil, or the pressure is too low, a compulsive oil feeding pump
such as shown in FIGS. 5A-6 should be provided in the sub-shaft 28 for
sufficient oil feeding.
FIGS. 5A and 5B show a trochoid-type oil feeding pump 61, which operates on
the principle of a general trochoid-type pump. The pump 61 comprises an
outer gear 62 and an inner gear 63, and the inner gear 63 rotates along
with the rotation rod 25. As both gears relatively rotate with each other,
oil is absorbed into the oil suction tube 41, transported from the suction
port 64 through the discharge port 65, and introduced into the oil feeding
hole 35 of the rotation rod 25.
FIG. 6 shows a spiral type oil feeding pump 71. The pump 71 comprises a
spiral blade 72, and is fit into the spiral groove 73 formed in the
sub-shaft 28. The pitch of the groove 73 is constantly set. As the
rotation rod 25 rotates, oil is absorbed into the oil suction tube 41, and
forcibly transported by the blade 72 in the direction indicated by the
arrow F.
Lastly, the present invention is not limited to the above-described
embodiment, and can be modified into a variety of versions as long as they
do not fall out of the range of the present invention.
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